This section provides background information related to the present disclosure which is not necessarily prior art.
As it is known, one of the defining characteristics of an electrical door latch is that it does not have mechanical linkages to outside and inside door handles. Instead, the door is released by an actuator in response to an electric signal coming from the handles.
Electrical door latches using double pawl arrangements normally comprise:
a ratchet biased by a spring into a release position, wherein the ratchet is positioned to receive or release a striker fixed to a door post, and which can be moved to a partially locked or first-click position and a fully locked or second-click position, in which the striker is increasingly retained inside the ratchet and prevented from withdrawing;
a primary pawl movable between a ratchet checking position, wherein the primary pawl is positioned to keep the ratchet in the partially locked or fully locked positions, and a ratchet release position, wherein the primary pawl permits the movement of the ratchet out of the partially locked or fully locked positions;
an auxiliary ratchet operatively connected to the primary pawl and movable between an enabling position, in which the primary pawl is enabled to move to its ratchet checking position, and a disabling position, in which the auxiliary ratchet positions the primary pawl to its ratchet release position;
a secondary pawl movable between an auxiliary ratchet holding position, in which the secondary pawl is positioned to hold the auxiliary ratchet in its enabling position, and an auxiliary ratchet release position, in which the secondary pawl is positioned to permit movement of the auxiliary ratchet to its disabling position;
an electrically-operated actuator assembly which can be selectively activated for moving the secondary pawl to the auxiliary ratchet release position and the auxiliary ratchet to the enabling position; and
an electrical control unit comprising a printed circuit board for controlling operation of the actuator assembly.
All the above-listed components are normally carried by a support body in turn secured to an edge of the vehicle door facing in use the door post carrying the striker; the latch is normally arranged in a door cavity also housing a window glass when lowered.
The double pawl arrangement consists in establishing a connection of a first set formed by the ratchet and the primary pawl with a second set formed by the auxiliary ratchet and the secondary pawl. The connection is configured such that only a portion of the forces experienced by the first set are applied to the second set, thus requiring only a relatively low effort to release the latch.
In conventional electrical latches, the support body normally carries the printed circuit board in a position parallel to the ratchet and to the edge of the door to which such latches are normally secured. The other mechanical components, such as the primary pawl, the auxiliary ratchet and the secondary pawl, are also carried in positions parallel to the ratchet and the printed circuit board.
Due to this kind of configuration, known latches have a considerable thickness in a direction orthogonal to the door edge to which the latches are secured; such direction is usually critical for the window glass or for the window glass channel path, i.e. the channel path followed by the window glass during its movements between raised and lowered positions. In certain cases, too large sizes of the thickness of the latches may influence the shape and style of the window glass.
Moreover, the above-described configuration is also problematic in cases in which it is required to isolate the electric part of the actuator assembly from the part of the latch subject to damp or water in order to prevent latch malfunctions in case the water penetrates into the latch, e.g. during raining or even in case of submerged vehicle.
Last but not least, due to the integration of the actuator assembly in the same body containing the ratchet and the other mechanical levers, the packaging of the latch has a significant size in the fixation plane; this could create issues to install the latch in different environments and customizations and may require a deep review or a complete redesign of the latch in case of different footprints, i.e. different positions of the fixation points in the door edge and different shapes and/or lengths of the opening in the door edge for receiving the striker, typically known as “fishmouth”.